JP2002318778A - Data communication system and data communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a data communication system which is adaptive to the USB2.0 standards by securely avoiding a time-out error based upon data transfer for computer peripheral equipment including a USB-adaptive printer. SOLUTION: A data reception area 11 provided in a printer 1 as an example of computer peripheral equipment and a computer 2 are interconnected through a 1st receiving buffer memory 101 for bulk-out transfer, a 2nd receiving buffer memory 102 for interrupt-out transfer, and a transmitting buffer 12 for interrupt- out transfer provided in the printer 1; and transfer modes are properly switched according to the processing state of data conversion in the computer peripheral equipment 1 and then the computer peripheral equipment 1 is made always ready for data reception.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a communication system using a serial bus, and more particularly, to a universal system.
The present invention relates to a data communication system conforming to the Serial Bus (hereinafter, referred to as “USB”) standard and a communication method thereof.

[0002]

2. Description of the Related Art Personal computers (hereinafter, "PC")
That. USB) is a serial bus interface standard established for data communication by connecting a PC) to multiple PC peripheral devices. This standard features simple connectivity and expandability not found in conventional interface standards.Many PC peripherals such as mice, keyboards, printers, scanners, and modems have recently become compatible with this USB. ing.

[0005] Here, the data flow will be briefly described by taking a USB-compatible printer as an example. First, print data transferred from a host PC to a printer is converted into data called a printer description language, It is temporarily stored in the reception buffer memory (FIFO memory) provided inside the controller. The printer stores print data (data called a printer description language) stored in the reception buffer memory in a data reception area of the internal memory of the printer. The print data stored in the data receiving area is moved to another area in the internal memory of the printer, and the conversion from the printer description language to the bitmap print data is executed. Then, printing is performed based on the bitmap print data. The time required for this conversion varies depending on the type and size of the print data or the state of the printer.

[0004] This means that the conversion processing to print data is quicker than the data transfer from the PC to the reception buffer memory, in other words, the data reception area always receives the data from the reception buffer memory. If the conversion from print data to print data cannot keep up with the transfer of data from the PC to the receive buffer memory, data transfer to the receive buffer memory is not possible. This causes a problem such as a timeout error.

[0005] The timeout error means that the state in which the print data cannot be transferred exceeds the set time for writing the entire print data from the host computer into the reception buffer.
In general, the user is notified by displaying a dialog window in which "Cancel printing" or the like is written.

Conventionally, an old-type printer such as a parallel connection automatically shifts to an intermittent printing mode when the free space of a receiving buffer of a printer controller becomes a predetermined value or less, and limits a receiving rate of print data. Thus, the receiving buffer memory is hard to be full. In this way, the timeout error is prevented by allowing the printer to accept the print data transfer little by little.

However, a USB having a large transfer data size per unit time (a data transfer rate of 12 Mbps
With the advent of a high-speed serial interface such as the USB 1.1 standard, the capacity required for the intermittent printing mode (most of the receiving buffer is used) is secured by using the conventional means. However, it is difficult for the printer to accept the print data transfer little by little, and the improvement has been desired.

[0008] In order to solve this problem,
There is a print control method disclosed in JP-A-2000-71570. In this method, a timeout error is generated by setting a longer timeout time on the USB port monitor and dynamically updating the set time according to at least one of the unit size and transfer rate of print data. Is to be suppressed.

[0009]

However, currently available USB devices include a USB device having a data transfer rate of 12 Mbps.
Although it is a 1.1 standard, the USB 2.0 standard with a data transfer rate of 480 Mbps was officially released in April 2000, and its application to high-speed data communication is expected.

[0010] Therefore, each PC peripheral device is compatible with the above-mentioned new standard.
The high-speed data transfer rate of 480Mbps is too large for the transfer data size, so that the standard cannot be fully utilized at the level of the conventional USB compatible printer, and even if the printer of that level is simply applied to the new standard, It is expected to cause a problem such as a timeout error.

That is, as described above, there is no problem as long as there is always a free space in the data receiving area of the printer.
In the standard High Speed mode, the possibility that the full state of the reception buffer memory continues for a long time is extremely high, and it is easily considered that the data transfer is frequently stopped due to a timeout error.

This is because the above-mentioned Japanese Patent Application Laid-Open No. 2000-71
It is considered that this also applies to the print control method disclosed in Japanese Patent No. 570. That is, JP-A-2000-7157
The method disclosed in Japanese Patent Publication No. 0 is a method in which the state on the PC side is controlled and does not improve the data communication path itself, so that it cannot cope with an extremely large amount of data transferred.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a data communication system and a communication method which are limited to a printer and a data communication system conforming to the USB 2.0 standard in which a timeout error based on data transfer is reliably avoided.

[0014]

To achieve the above object, a first aspect of the present invention is a data communication system in which a computer and a computer peripheral device are connected so as to be capable of two-way communication based on a data communication standard. In the above, the data reception area provided in the computer peripheral device and the computer are provided with a plurality of switchable reception buffer memories provided in the peripheral device and receiving data, and the data reception area state provided in the peripheral device. Connected to the computer via at least one transmission buffer memory, and the computer switches the reception buffer memory based on the state of the data reception area and the state of the reception buffer to switch the reception buffer. Data stored in the memory and stored according to the state of the reception area Lying in the data communication system characterized always peripherals gradually transferred to the data receiving area is receivable in the configuration data.

According to the above technical means, when the computer examines the state of the data reception area of the PC peripheral device and determines that there is no free space in the data reception area and a timeout error may occur, A plurality of reception buffer memories provided on the PC peripheral device side are appropriately switched, and data is stored in the reception buffer memories. And PC
The data stored in the vacant data receiving area is gradually transferred as the processing of the peripheral device progresses.

According to a second aspect of the present invention, in the first aspect, the reception buffer memory includes a first reception buffer memory and a second reception buffer memory, and the first reception buffer memory is a USB2. 0 for bulk out transfer
The data communication system is characterized in that the second reception buffer memory is a FIFO memory for interrupt out transfer according to the USB 2.0 standard, and the second reception buffer memory is a FIFO memory.

According to the above technical means, the first reception buffer memory is limited to the FIFO memory for USB2.0 standard bulk-out transfer, and the second reception buffer memory is used for USB2.0 standard interrupt-out transfer. In this case, the data transfer mode between the PC and the peripheral device can be selected according to the state of the PC peripheral device.

That is, the transfer mode of the first reception buffer memory is set to the USB 2.0 standard bulk-out transfer. In this bulk-out transfer, the transfer data is divided into 512-byte packets and transferred to the first reception buffer memory. If there is free space in the USB bus traffic, the data transfer is frequently performed.

However, when only the bulk-out transfer is used as the transfer mode of the receiving buffer memory, the data receiving area of the printer is likely to be full, and the possibility of a timeout error increases.

Therefore, the transfer mode of the second reception buffer memory is set to the interrupt transfer mode. This interrupt transfer reduces the transfer data size per packet to 10
It can be set to any value of 24 bytes or less, and the data transfer occurrence interval can also be selected. That is, by using a transfer data size of several bytes and increasing the interval of data transfer, the effective data transfer rate can be reduced as compared with the bulk-out transfer via the first reception buffer memory. It is possible.

Therefore, it is extremely unlikely that the second reception buffer memory will become full and will not accept data reception, and will continue to receive data from the host PC even in small quantities, thereby suppressing the occurrence of timeout errors. You can do it.

According to a third aspect of the present invention, there is provided the data communication system according to the second aspect, wherein the transmission buffer memory is a FIFO memory for interrupt-in transfer of USB 2.0 standard.

According to the above technical means, as described above, the USB2.0 standard FIFO memory for interrupt-in transfer capable of performing an interrupt-in transfer capable of a smaller effective data transfer rate than the bulk-out transfer is employed. And the second
In parallel with the data reception using the reception buffer memory, the host PC periodically checks the status of the data reception area of the printer. When a sufficient free space for the bulk-out transfer is secured in the data reception area of the printer, the data transfer destination is switched to the first reception buffer memory again.

According to a fourth aspect of the present invention, there is provided the data communication system according to the second aspect, wherein the transmission buffer memory is a FIFO memory for bulk-in transfer according to the USB 2.0 standard.

The USB standard supports four transfer modes: control transfer, interrupt transfer, bulk transfer, and isochronous transfer. The USB standard defines device class specifications for each application. For example, in the case of a printer, a configuration according to the printer class specifications is recommended. As shown in FIG. 3, as a bidirectional configuration of the printer class specification, a bulk-out transfer mode is used for transfer of print data from the host PC to the printer, and a bulk-in transfer mode is used for transfer of printer status data from the printer to the host PC. It is recommended to use

According to a fifth aspect of the present invention, in the first aspect, the transmission buffer memory stores empty state data of the data reception area which is recognized according to a status of a data conversion process. Is transferred to a computer.

According to a sixth aspect of the present invention, in the fifth aspect, the first data is stored on the basis of the remaining state of data in the reception buffer memory and the free state data of the data reception area.
6. The data communication system according to claim 5, wherein said receiving buffer memory and said second receiving buffer memory are switched by a computer.

According to a seventh aspect of the present invention, in the sixth aspect, the data transmitted from the computer is stored in the first reception buffer memory, and the stored data is stored when the free space of the data reception area becomes zero or less than a set value. First means for transferring data to the data reception area until the data reception area becomes zero or less than or equal to a set value. And a second means for receiving and storing data in the second reception buffer memory, and a second means for receiving a free space in the data receiving area by the data conversion processing of the computer peripheral device progressing. First from buffer memory
A third means for transferring only the data remaining in the first buffer memory to the data receiving area when the computer switches to the second buffer memory while the computer switches to the second buffer memory. And after transferring only the data remaining in the first buffer memory to the data receiving area, the computer switches from the second receiving buffer memory to the first receiving buffer memory and switches to the first receiving buffer memory. Fourth means for receiving and storing the data and transferring the data stored in the second buffer memory to the data reception area, and transferring the data stored in the second buffer memory to the data reception area. And a fifth means for transferring the data stored in the first reception buffer memory to the data reception area.
The data communication system is characterized in that the first reception buffer memory and the second reception buffer memory are switched.

An eighth aspect of the present invention is the data communication system according to any one of the third to seventh aspects, wherein the computer peripheral device is a printer.

A ninth aspect of the present invention is a data communication method in a data communication system in which a computer and a computer peripheral device are connected so as to be capable of two-way communication based on a data communication standard. The provided data reception area and the computer are provided with the switchable first and second reception buffer memories provided in the peripheral device and receiving data, and the status of the data reception area provided in the peripheral device to the computer. Connected via a transmission buffer memory to be transferred, and the computer switches between the first and second reception buffer memories based on a state of the data reception area and a state of the first and second reception buffer memories. To store the data in the reception buffer memory and gradually store the stored data in accordance with the state of the reception area. Always peripheral device by transferring the data receiving area is in data communication method being characterized in that to enable data reception.

According to a tenth aspect of the present invention, in the ninth aspect,
A first step of storing data transmitted from the computer in a first reception buffer memory and transferring the stored data to a data reception area until the free space of the data reception area becomes zero or less than a set value; The computer switches from the first reception buffer memory to the second reception buffer memory in response to the fact that the empty state of the data reception area becomes zero or less than the set value, and receives and stores the data in the second reception buffer memory. A second step of performing the data conversion processing of the computer peripheral device, and in response to the fact that the capacity of the data receiving area becomes available, the computer switches from the second buffer memory to the first buffer memory, Only the data remaining in the first buffer memory when switching from the first buffer memory to the second buffer memory is replaced with the data A third step of transferring the data remaining in the first buffer memory to the data receiving area, and then transferring the data from the second receiving buffer memory to the first receiving buffer memory. A fourth step of switching and receiving and storing the data in the first reception buffer memory, and simultaneously transferring the data stored in the second buffer memory to the data reception area; and storing the data in the second buffer memory. Transferring the data stored in the first reception buffer memory to the data reception area after transferring the data to the data reception area; and
The data communication method is characterized by switching between the first reception buffer memory and the second reception buffer memory.

[0032]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. As shown in FIG.
The data communication system includes a printer 1 that converts a printer description language into bitmap print data and outputs a desired print based on the data, a host PC2 that transmits the printer description language and controls the printer, a printer 1 and a host PC2. And a USB cable 3 for connecting the

The printer has a receiving buffer memory 10,
It comprises a data reception area 11 and a transmission buffer memory 12.

The reception buffer memory 10 includes a first reception buffer memory 101 composed of a USB 2.0 standard FIFO memory for bulk-out transfer and a second reception buffer composed of a USB 2.0 standard FIFO memory for interrupt-out transfer. And a memory 102. When the data capacity of each of the buffers 10 is illustrated, for example, the first reception buffer 101
Is 1024 bytes, and the second reception buffer memory 102
Is 256 bytes.

As shown in FIG. 2, the reception buffer memory 10 is provided between the host PC 2 and a data reception area 11 to be described later. Data receiving area 1
1 are connected in two types of data transfer modes, bulk-out transfer and interrupt-out transfer.

The path for each reception buffer memory 10 connecting the host PC 2 and a data reception area 11 described later has the following functions. • Path A1 to host PC2 and first reception buffer memory 10
This is a path for bulk-out transfer of printer data communication data between one unit, and data communication is performed in units of 512 bytes. Path A2 to host PC 2 and second reception buffer memory 10
This is a path for interrupt-out transfer of printer data communication data between the two, and data communication is performed in units of 4 bytes. Path B1 is a path for transferring printer data communication data between the first reception buffer memory 101 and the data reception area 11. Path B2—A path for transferring printer data communication data between the second reception buffer memory 102 and the data reception area 11.

The data reception area 11 is an area of the printer internal memory provided in the printer 1 and stores print data stored in the reception buffer memory 10. The print data stored in the data reception area 11 is further moved to another area in the internal memory of the printer device, and is converted from the printer description language, which is the print data, to bitmap print data. The free space in the data receiving area 11 constantly changes in accordance with the progress of the data conversion, and the time required for the conversion varies depending on the type and size of the print data or the state of the printer.

The transmission buffer memory 12 is composed of a USB 2.0 standard interrupt-in transfer FIFO memory provided between the host PC 2 and the data reception area 11, and as shown in FIG. 11 in an interrupt-out transfer mode. The transmission buffer memory 12 is a relay point for storing the above-mentioned empty state data of the data reception area 11 and transferring the data to a computer.

The path of the transmission buffer memory 12 connecting the host PC 2 and the data reception area 11 has the following functions. Route A3—A route for interrupt-in transfer of data reception area information data (free area information) between the host PC 2 and the transmission buffer memory 12. -Route B3-transmission buffer memory 12 and data reception area 1
This is a path for transferring data reception area information data (empty area information) between one unit, and the transfer speed and the data transfer unit are not particularly defined.

The host PC 2 periodically checks the state of the data receiving area 11 of the printer 1 described later, and if it determines that there is not enough free space in the data receiving area 11 of the printer 1 for bulk-out transfer, Switching from the first reception buffer memory 101 provided on the peripheral device side of the host PC 2 to the second reception buffer memory 102, and when it is determined that the data has been secured in the data reception area 11, the data transfer destination is changed to the first reception buffer memory again. A function for switching to the memory 101 is provided.

The USB cable 3 is a cable having a well-known structure based on the USB standard. The USB cable 3 is connected to a connection portion (not shown) formed on the side of the case constituting the printer main body and is formed on the side of the case constituting the host PC 1 main body. Connection section (not shown).

The data transfer control procedure between the host PC 2 and the data reception area 11 provided in the printer 1 in the data communication system configured as described above is as follows. 1) Printer data is stored in the first reception buffer memory 101 via the path A1. The data in the first reception buffer memory 101 is transferred to the data reception area 1 via the path B1.
Transferred to 1. 2) The path until the data reception area 11 becomes full and the first reception buffer memory 101 cannot receive data.
Transfer via A1 and route B1 is performed. 3) The state of the free space of the data reception area 11 is periodically determined by the host PC via the path B3 → the transmission buffer memory 12 → the path A3.
2 has been transferred. The host PC 2 has a data receiving area 11
When the free space becomes zero or less than a certain value, the storage destination of the print data is switched from the first reception buffer memory 101 to the second reception buffer memory 102.

4) The printer data is stored in the second reception buffer memory 102 via the path A2. Data transfer to the data reception area 11 via the path B2 is not performed. 5) When the data processing (printer language bitmap conversion) on the printer 1 side progresses, free space is generated in the data receiving area 11, and the data in the first receiving buffer memory 101 is transferred to the data receiving area via the path B1. Transfer to 11 is resumed. The state of the free space of the data reception area 11 is indicated by the route B3.
→ Transmission buffer memory 12 → Host PC 2 via path A3
The host PC 2 switches the print data storage destination from the second reception buffer memory 102 to the first reception buffer memory 101. At this time, in order to distinguish the data before and after the switching of the reception buffer memory 10 (the data remaining in the first reception buffer memory 101), the data in the first reception buffer memory 101 at the time of the switching of the reception buffer memory 3). The amount is recorded, and control is performed based on the information, so that the transfer order of the print data is not reversed.

6) The data in the first reception buffer memory 101 is transferred to the data reception area 11 via the path B1 by the amount of the stored data. 7) The transfer from the path B1 is interrupted, and all data in the second reception buffer memory 102 is transferred to the data reception area 11 via the path B2. 8) When the transfer of all data in the second reception buffer memory 102 is completed, the transfer from the path B1 is restarted. 9) In steps 5) to 8), the transfer of the print data to the first reception buffer memory 101 via the path A1 is continuously performed, and the state returns to the state of 1).

As described above, when the host PC 2 periodically checks the state of the data receiving area 11 of the printer 1 and determines that there is no free space in the data receiving area 11 and a timeout error may occur. First, the first reception buffer memory 101 and the second reception buffer memory 102 provided on the printer 1 side are appropriately switched, data is temporarily stored in the reception buffer memory 10, and the state of the data reception area 11, that is, By gradually transferring the data stored in the empty data receiving area 11 as the processing of the printer 2 progresses, a time-out occurs due to the state where print data from the host PC 2 cannot be transferred for a certain period of time or more. The occurrence of errors is effectively suppressed.

In this embodiment, the transmission buffer memory is provided between the host PC 1 and the data reception area.
Although the FIFO memory for interrupt-in transfer according to the USB 2.0 standard is used, a FIFO memory for bulk-in transfer may be used instead of this as shown in FIG. In this case, the information of the free space in the data receiving area of the printer obtained by the host PC is not always obtained from the function. However, unless a large number of PC peripheral devices other than the printer are connected to the host PC, the present embodiment will be described. Works without any problems with the control procedure.

Further, in the present embodiment, the transmission buffer memory is provided with an interrupt-in transfer FI for the USB 2.0 standard.
Although only a single FO memory is illustrated, the present invention is not limited to this. The FIFO for bulk-in transfer is similar to the reception buffer.
The data transfer mode between the PC and the peripheral device may be selected using a memory and an interrupt-in transfer FIFO memory. In this case, if the PC peripheral device is chain-connected to the PC, troubles caused by differences in the hardware configuration environment, and even if the PC peripheral device is a single unit, grasp the state of the data reception area for a certain period of time When a trouble such as data not being transferred to the PC occurs, it is possible to automatically switch the transfer mode and try a response.

The control function provided in the host PC 1 for achieving the present invention is preferably in the form of a recording medium on which the function is recorded. A limited data communication system can be constructed.

The data communication method according to the data transfer control procedure in the data communication system exemplified in this embodiment may be used.

[0050]

As described above, the present invention has the following advantageous effects. According to the first aspect, when the computer examines the state of the data reception area of the PC peripheral device and determines that there is no free space in the data reception area and a timeout error may occur, the computer peripheral device side The data is stored in the reception buffer memory by appropriately switching the plurality of reception buffers provided in the PC, and the data stored in the vacant data reception area is gradually transferred as the processing of the PC peripheral device progresses. Therefore, the PC peripheral device always accepts data, and can reliably avoid a timeout error due to data transfer.

According to the second aspect, in the first aspect, the first reception buffer memory is limited to a FIFO memory for bulk-out transfer conforming to the USB 2.0 standard, and the second reception buffer memory is conforming to the USB 2.0 standard. By limiting to the FIFO memory for interrupt-out transfer, the data transfer mode between the PC and the peripheral device can be selected according to the state of the PC peripheral device. Can be set to the bulk-out transfer mode when transferring data (normal transfer), and to the interrupt transfer mode in which the transfer data size can be set to an arbitrary value when a timeout error is likely to occur. It is extremely unlikely that data will be lost, and it will continue to receive data from the host PC even in small increments, thus reducing the occurrence of timeout errors. It can be.

According to the third aspect of the present invention, the transmission buffer memory is a FIFO memory for interrupt-in transfer of the USB 2.0 standard, so that the host PC can execute the data reception using the second reception buffer memory in parallel. The status of the data receiving area of the printer can be checked periodically.

According to claim 4, in claim 3, the FIFO memory for bulk-in transfer is replaced with the FIFO memory for interrupt-in transfer of the USB 2.0 standard.
A data communication system having a transfer mode suitable for a printer class recommended by the standard can be provided.

According to a fifth aspect, in any one of the first to fourth aspects, the transmission buffer memory stores empty state data of the data reception area which is recognized in accordance with the status of data conversion processing. Has been configured to transfer data to a computer, and the status of the data conversion process can be indirectly determined by this easily available data.
Can be recognized.

According to a sixth aspect, in the fifth aspect, the first reception buffer memory and the second reception buffer memory based on the remaining state of data in the reception buffer and the empty state data of the data reception area. Is configured to be switched by the computer, the transfer order of the print data can be surely maintained by switching the reception buffer while also grasping the remaining state of the data.

According to the seventh aspect, when there is a possibility that a time-out error may occur, the first means to the fifth means are repeated so that the computer peripheral device is always configured to receive data. In addition, it is possible to provide a suitable data communication system that is compatible with the USB 2.0 standard while reliably avoiding a timeout error based on data transfer.

According to the eighth aspect, since the computer peripheral device is limited to a printer, it is possible to provide a suitable printer system compatible with the USB 2.0 standard while reliably avoiding a timeout error due to data transfer. it can.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an outline of a data communication system according to the present invention.

FIG. 2 is an explanatory diagram showing a flow of data in the printer according to the present invention.

FIG. 3 is an explanatory diagram when a transmission buffer memory is bulk-in with respect to a conventional system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Printer 2 Host PC 10 Reception buffer memory 101 First reception buffer memory 102 Second reception buffer memory 11 Data reception area 12 Transmission buffer memory

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Claims (10)

[Claims] 1. A data communication system in which a computer and a computer peripheral device are connected so as to be capable of two-way communication based on a data communication standard, wherein a data reception area provided in the computer peripheral device and the computer are connected to each other. Connected via a plurality of switchable reception buffer memories provided in the peripheral device for receiving data and at least one transmission buffer memory provided in the peripheral device for transferring a data reception area state to a computer. The computer switches the reception buffer memory based on the state of the data reception area and the state of the reception buffer, stores the data in the reception buffer memory, and stores the data in accordance with the state of the reception area. Data is gradually transferred to the data reception area and the peripheral device can always accept data Data communication system characterized in that it is configured to. 2. The reception buffer memory comprises a first reception buffer memory and a second reception buffer memory, wherein the first reception buffer memory is a FIFO memory for bulk-out transfer according to USB 2.0 standard. 2. The data communication system according to claim 1, wherein said second reception buffer memory is a FIFO memory for interrupt-out transfer of USB 2.0 standard. 3. The data communication system according to claim 2, wherein said transmission buffer memory is a FIFO memory for interrupt-in transfer of USB 2.0 standard. 4. The data communication system according to claim 2, wherein said transmission buffer memory is a FIFO memory for bulk-in transfer of USB 2.0 standard. 5. The transmission buffer memory according to claim 1, wherein empty data of the data reception area recognized according to a status of a data conversion process is stored, and the data is transferred to a computer. 5. The data communication system according to any one of 4. 6. A computer according to claim 1, wherein said first reception buffer memory and said second reception buffer memory are switched by a computer based on a remaining state of data in said reception buffer memory and empty state data of said data reception area. The data communication system according to claim 5, wherein 7. A first method for storing data transmitted from a computer in a first reception buffer memory and transferring the stored data to the data reception area until the free space of the data reception area becomes zero or less than a set value. Means for switching from the first receiving buffer memory to the second receiving buffer memory in response to the fact that the empty state of the data receiving area has become zero or less than a set value, and the second receiving buffer memory And a second means for receiving and storing data in the first buffer memory from the second buffer memory in response to the fact that the data conversion processing of the computer peripheral device has progressed and the capacity of the data receiving area has become free. When the computer switches, the second buffer memory
A third means for transferring only data remaining in the first buffer memory to the data receiving area when switching to the first buffer memory, and receiving only the data remaining in the first buffer memory. After the transfer to the area, the computer switches from the second reception buffer memory to the first reception buffer memory, receives and stores the data in the first reception buffer memory, and simultaneously stores the data stored in the second buffer memory. Fourth means for transferring the data stored in the second buffer memory to the data reception area, and then transferring the data stored in the first reception buffer memory to the data reception area. A fifth means for transferring to an area switches between the first reception buffer memory and the second reception buffer memory. 6 data communication system described. 8. The data communication system according to claim 3, wherein the computer peripheral device is a printer. 9. A data communication method in a data communication system in which a computer and a computer peripheral device are connected so as to be capable of two-way communication based on a data communication standard, and wherein a data reception method provided in the computer peripheral device is provided. Switchable first and second reception buffer memories provided in the peripheral device for receiving data, and a transmission buffer memory provided in the peripheral device for transferring a data reception area state to the computer. The computer switches between the first and second reception buffer memories based on the state of the data reception area and the states of the first and second reception buffer memories. The data is stored into the data receiving area according to the state of the receiving area. Data communication method always peripherals and is characterized in that to enable data reception. 10. A first method for storing data transmitted from a computer in a first reception buffer memory and transferring the stored data to the data reception area until the free space of the data reception area becomes zero or less than a set value. And the computer switches from the first reception buffer memory to the second reception buffer memory in response to the empty state of the data reception area being reduced to zero or less than a set value, and the second reception buffer memory A second step of receiving and storing the data in the second buffer memory, and in response to the fact that the data conversion processing of the computer peripheral device has progressed and the capacity of the data receiving area has become free, the second buffer memory transfers the data to the first buffer memory. When the computer switches, the second buffer memory
A third step of transferring only data remaining in the first buffer memory to the data receiving area when switching to the first buffer memory, and receiving only the data remaining in the first buffer memory. After the transfer to the area, the computer switches from the second reception buffer memory to the first reception buffer memory, receives and stores the data in the first reception buffer memory, and simultaneously stores the data stored in the second buffer memory. Transferring the data stored in the second buffer memory to the data receiving area, and transferring the data stored in the first receiving buffer memory to the data receiving area. 10. The method according to claim 9, further comprising: switching between the first reception buffer memory and the second reception buffer memory in the fifth step of transferring to an area. Data communication method of the mounting.